To decide who adds new blocks and what data goes into them, Ethereum uses consensus: a shared agreement process among many computers.

The voters in this process are called validators. Each validator locks up 32 ETH, so votes are weighted by staked ETH instead of by the number of computers someone runs. This is called Proof of Stake.

Validators can propose blocks, meaning they suggest the next block to add. Other validators check those blocks and attest, which means they vote that a block follows the rules.

Validators can be slashed for signing conflicting votes, meaning they vote two different ways when they should only vote once. Slashed means some stake is taken away as a penalty. Offline validators can also lose small amounts. Honest validators earn rewards for helping secure the network.